In vitro evaluation of prebiotic activity, pathogen inhibition and enzymatic metabolism of intestinal bacteria in the presence of fructans extracted from agave: A comparison based on polymerization degree

The prebiotic effect of fructans is well known, including their beneficial influence on health. This study shows agave fructans impact as potential prebiotics, depending on their structure and polymerization degree (PD). The growth of seven probiotics and three pathogens was estimated by turbidimetric analysis and the latter (Salmonella typhimurium, Staphylococcus aureus and Listeria monocytogenes) were submitted to growth inhibition tests in the presence of metabolites produced by probiotics. Lactobacillus casei and L. paracasei growth was optimal when supplemented with agave fructans. L. casei was grown in the presence of the extracted fractions obtained from Agave salmiana spp. crassipina (optical density (O.D.) 1.09 ± 0.02, 0.98 ± 0.03, 0.98 ± 0.07, low, medium and high PD, respectively), A. salmiana var. liso (0.85 ± 0.13), A. atrovirens (0.79 ± 0.03) and A. tequilana spp. (0.89 ± 0.03). The growth of L. paracasei was optimal when supplemented with those fractions obtained from the A. salmiana (O.D. 1.12 ± 0.02, 1.18 ± 0.02, 1.13 ± 0.007, low, medium and high PD, respectively) and A. tequilana var. cenizo (1.18 ± 0.01 and 1.15 ± 0.02, medium and high PD, respectively) species. Both bacteria were tested in order to assess enzyme activity using API ZYM galleries after they were grown on agave fructans. The results show an increase of five enzymes (cysteine-arylamidase, α-chymotrypsin, β-galactosidase, N-acetyl-β-glucosaminidase and α-fucosidase).